implement comparisons

1 files changed, 31 insertions, 4 deletions

diff --git a/src/parse.zig b/src/parse.zig
index e675fbe..efb5c8e 100644
--- a/src/parse.zig
+++ b/src/parse.zig
@@ -96,11 +96,19 @@ pub const Expr = struct {
             const Op = enum {
                 plus,
                 minus,
+                left_angle,
+                right_angle,
+                left_angle_equal,
+                right_angle_equal,
 
                 pub fn format(self: Op, comptime _: []const u8, _: std.fmt.FormatOptions, writer: anytype) !void {
-                    try writer.writeByte(switch (self) {
-                        .plus => '+',
-                        .minus => '-',
+                    try writer.writeAll(switch (self) {
+                        .plus => "+",
+                        .minus => "-",
+                        .left_angle => "<",
+                        .right_angle => ">",
+                        .left_angle_equal => "<=",
+                        .right_angle_equal => ">=",
                     });
                 }
             };
@@ -210,7 +218,26 @@ pub fn statement(allocator: Allocator, lexer: *Lexer) ParseError!Stmt {
 }
 
 pub fn expression(allocator: Allocator, lexer: *Lexer) ParseError!*Expr {
-    return parseTerms(allocator, lexer);
+    return parseComparisons(allocator, lexer);
+}
+
+pub fn parseComparisons(allocator: Allocator, lexer: *Lexer) ParseError!*Expr {
+    const lhs = try parseTerms(allocator, lexer);
+
+    const op: Expr.Type.BinOp.Op = switch (lexer.peek().type) {
+        .left_angle => .left_angle,
+        .right_angle => .right_angle,
+        .left_angle_equal => .left_angle_equal,
+        .right_angle_equal => .right_angle_equal,
+        else => return lhs,
+    };
+    _ = lexer.next();
+
+    const rhs = try parseTerms(allocator, lexer);
+    return try allocate(Expr, allocator, .{
+        .loc = lhs.loc.combine(rhs.loc),
+        .type = .{ .bin_op = .{ .lhs = lhs, .op = op, .rhs = rhs } },
+    });
 }
 
 pub fn parseTerms(allocator: Allocator, lexer: *Lexer) !*Expr {